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|
/*
* The GNS Socks5 Proxy
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/epoll.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <microhttpd.h>
#include "protocol.h"
#define MAXEVENTS 64
#define DEBUG 1
/*
* Create an ipv4/6 tcp socket for a given port
*
* @param port the port to bind to
* @return the file descriptor of the socket or -1
*/
static int
create_socket (char *port)
{
struct addrinfo hints;
struct addrinfo *result, *rp;
int s, sfd;
memset (&hints, 0, sizeof (struct addrinfo));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_flags = AI_PASSIVE;
s = getaddrinfo (NULL, port, &hints, &result);
if (s != 0)
{
fprintf (stderr, "getaddrinfo: %s\n", gai_strerror (s));
return -1;
}
for (rp = result; rp != NULL; rp = rp->ai_next)
{
sfd = socket (rp->ai_family, rp->ai_socktype, rp->ai_protocol);
if (sfd == -1)
continue;
s = bind (sfd, rp->ai_addr, rp->ai_addrlen);
if (s == 0)
{
break;
}
close(sfd);
}
if (rp == NULL)
{
fprintf (stderr, "Could not bind\n");
return -1;
}
freeaddrinfo (result);
return sfd;
}
/*
* Make socket with fd non blocking
*
* @param fd the file descriptor of the socket
* @return -1 on error
*/
static int
setnonblocking (int fd)
{
int flags, s;
flags = fcntl (fd, F_GETFL, 0);
if (flags == -1)
{
perror ("fcntl");
return -1;
}
flags |= O_NONBLOCK;
s = fcntl (fd, F_SETFL, flags);
if (s == -1)
{
perror ("fcntl");
return -1;
}
return 0;
}
/**
* Checks if name is in tld
*
* @param name the name to check
* @param tld the TLD to check for
* @return -1 if name not in tld
*/
static int
is_tld (const char* name, const char* tld)
{
int offset = 0;
if (strlen (name) <= strlen (tld))
return -1;
offset = strlen (name) - strlen (tld);
if (strcmp (name+offset, tld) != 0)
return -1;
return 0;
}
/*
* Connect to host specified in phost
*
* @param phost the hostentry containing the IP
* @return fd to the connection or -1 on error
*/
static int
connect_to_domain (struct hostent* phost, uint16_t srv_port)
{
uint32_t srv_ip;
struct sockaddr_in srv_addr;
struct in_addr *sin_addr;
int conn_fd;
sin_addr = (struct in_addr*)(phost->h_addr);
srv_ip = sin_addr->s_addr;
conn_fd = socket(AF_INET, SOCK_STREAM, 0);
memset(&srv_addr, 0, sizeof(srv_addr));
srv_addr.sin_family = AF_INET;
srv_addr.sin_addr.s_addr = srv_ip;
srv_addr.sin_port = srv_port;
printf("target server: %s:%u\n", inet_ntoa(srv_addr.sin_addr),
ntohs(srv_port));
if (connect (conn_fd, (struct sockaddr*)&srv_addr,
sizeof (struct sockaddr)) < 0)
{
printf("socket request error...\n");
close(conn_fd);
return -1;
}
setnonblocking(conn_fd);
return conn_fd;
}
static struct MHD_Daemon *mhd_daemon;
static int
access_cb (void* cls,
const struct sockaddr *addr,
socklen_t addrlen)
{
printf ("access cb called\n");
return MHD_YES;
}
static int
accept_cb (void *cls,
struct MHD_Connection *con,
const char *url,
const char *meth,
const char *ver,
const char *upload_data,
size_t *upload_data_size,
void **con_cls)
{
static int dummy;
const char* page = "<html><head><title>gnoxy</title>"\
"</head><body>gnoxy demo</body></html>";
struct MHD_Response *response;
int ret;
if (0 != strcmp (meth, "GET"))
return MHD_NO;
if (&dummy != *con_cls)
{
*con_cls = &dummy;
return MHD_YES;
}
if (0 != *upload_data_size)
return MHD_NO;
*con_cls = NULL;
response = MHD_create_response_from_data (strlen(page),
(void*) page,
MHD_NO,
MHD_NO);
ret = MHD_queue_response (con, MHD_HTTP_OK, response);
MHD_destroy_response (response);
return ret;
}
int main ( int argc, char *argv[] )
{
int sfd, s;
int efd;
struct epoll_event event;
struct epoll_event *events;
int ev_states[MAXEVENTS];
int n, i, j;
struct socks5_bridge* br;
struct sockaddr in_addr;
socklen_t in_len;
int infd;
char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
int done;
ssize_t count;
char buf[512];
struct socks5_server_hello hello;
struct socks5_server_response resp;
struct socks5_client_request *req;
struct socks5_bridge* new_br;
char domain[256];
uint8_t msg[16];
uint8_t dom_len;
uint16_t req_port;
int conn_fd;
struct hostent *phost;
mhd_daemon = NULL;
for (j = 0; j < MAXEVENTS; j++)
ev_states[j] = SOCKS5_INIT;
if (argc != 2)
{
fprintf (stderr, "Usage: %s [port]\n", argv[0]);
exit (EXIT_FAILURE);
}
sfd = create_socket(argv[1]);
if (s == -1)
abort ();
s = setnonblocking (sfd);
if (s == -1)
abort ();
s = listen (sfd, SOMAXCONN);
if (s == -1)
{
perror ("listen");
abort ();
}
efd = epoll_create1 (0);
if (efd == -1)
{
perror ("epoll create");
abort ();
}
br = malloc(sizeof (struct socks5_bridge));
event.data.ptr = br;
br->fd = sfd;
br->remote_end = NULL;
event.events = EPOLLIN | EPOLLET;
s = epoll_ctl (efd, EPOLL_CTL_ADD, sfd, &event);
if (s == -1)
{
perror ("epoll ctl");
abort ();
}
events = calloc (MAXEVENTS, sizeof event);
while (1)
{
n = epoll_wait (efd, events, MAXEVENTS, -1);
for (i = 0; i < n; i++)
{
br = (struct socks5_bridge*)(events[i].data.ptr);
if ((events[i].events & EPOLLERR) ||
(events[i].events & EPOLLHUP) ||
(!(events[i].events & EPOLLIN)))
{
fprintf (stderr, "epoll error %d\n", events[i].events);
fprintf (stderr, "closing fd %d\n", br->fd);
close (br->fd);
continue;
}
else if (sfd == br->fd)
{
/* New connection(s) */
while (1)
{
in_len = sizeof (in_addr);
infd = accept (sfd, &in_addr, &in_len);
if (infd == -1)
{
if ((errno == EAGAIN) ||
(errno == EWOULDBLOCK))
{
break;
}
else
{
perror ("accept");
break;
}
}
s = getnameinfo (&in_addr, in_len,
hbuf, sizeof (hbuf),
sbuf, sizeof (sbuf),
NI_NUMERICHOST | NI_NUMERICSERV);
if (s == -1)
abort ();
s = setnonblocking (infd);
if (s == -1)
abort ();
event.events = EPOLLIN | EPOLLET;
br = malloc (sizeof (struct socks5_bridge));
br->fd = infd;
br->addr = in_addr;
br->addr_len = in_len;
br->remote_end = NULL;
br->status = SOCKS5_INIT;
event.data.ptr = br;
s = epoll_ctl (efd, EPOLL_CTL_ADD, infd, &event);
if (s == -1)
{
perror ("epoll ctl");
abort ();
}
}
continue;
}
else
{
/* Incoming data */
done = 0;
while (1)
{
count = read (br->fd, buf, sizeof (buf));
if (count == -1)
{
if (errno != EAGAIN)
{
perror ("read");
done = 1;
}
break;
}
else if (count == 0)
{
done = 1;
break;
}
if (br->status == SOCKS5_DATA_TRANSFER)
{
if (DEBUG)
{
printf ("Trying to fwd %d bytes from %d to %d!\n" ,
count, br->fd, br->remote_end->fd );
}
if (br->remote_end)
s = write (br->remote_end->fd, buf, count);
if (DEBUG)
printf ("%d bytes written\n", s);
}
if (br->status == SOCKS5_INIT)
{
hello.version = 0x05;
hello.auth_method = 0;
write (br->fd, &hello, sizeof (hello));
br->status = SOCKS5_REQUEST;
}
if (br->status == SOCKS5_REQUEST)
{
req = (struct socks5_client_request*)buf;
memset(&resp, 0, sizeof(resp));
if (req->addr_type == 3)
{
dom_len = *((uint8_t*)(&(req->addr_type) + 1));
memset(domain, 0, sizeof(domain));
strncpy(domain, (char*)(&(req->addr_type) + 2), dom_len);
req_port = *((uint16_t*)(&(req->addr_type) + 2 + dom_len));
phost = (struct hostent*)gethostbyname (domain);
if (phost == NULL)
{
printf ("Resolve %s error!\n" , domain );
resp.version = 0x05;
resp.reply = 0x01;
write (br->fd, &resp, sizeof (struct socks5_server_response));
break;
}
if ( -1 != is_tld (domain, ".gnunet") )
{
if (NULL == mhd_daemon)
{
mhd_daemon = MHD_start_daemon( MHD_USE_THREAD_PER_CONNECTION,
8080,
&access_cb, br,
&accept_cb, br,
MHD_OPTION_END);
}
printf ("trying to add to MHD\n");
if (MHD_YES != MHD_add_connection (mhd_daemon,
br->fd,
&br->addr,
br->addr_len))
{
printf ("Error adding %d to mhd\n", br->fd);
}
event.events = EPOLLIN | EPOLLET;
epoll_ctl (efd, EPOLL_CTL_DEL, br->fd, &event);
resp.version = 0x05;
resp.reply = 0x00;
resp.reserved = 0x00;
resp.addr_type = 0x01;
write (br->fd, &resp, 10);
break;
}
conn_fd = connect_to_domain (phost, req_port);
if (-1 == conn_fd)
{
resp.version = 0x05;
resp.reply = 0x01;
write (br->fd, &resp, 10);
}
else
{
if (DEBUG)
printf("new remote connection %d to %d\n", br->fd, conn_fd);
resp.version = 0x05;
resp.reply = 0x00;
resp.reserved = 0x00;
resp.addr_type = 0x01;
new_br = malloc (sizeof (struct socks5_bridge));
br->remote_end = new_br;
br->status = SOCKS5_DATA_TRANSFER;
new_br->fd = conn_fd;
new_br->remote_end = br;
new_br->status = SOCKS5_DATA_TRANSFER;
event.data.ptr = new_br;
event.events = EPOLLIN | EPOLLET;
epoll_ctl (efd, EPOLL_CTL_ADD, conn_fd, &event);
write (br->fd, &resp, 10);
}
}
else
{
printf("not implemented address type %02X\n", (int)req->addr_type);
}
}
if (s == -1)
{
perror ("write");
abort ();
}
}
if (done)
{
close (br->fd);
if (br->remote_end)
{
close (br->remote_end->fd);
free(br->remote_end);
}
free(br);
}
}
}
}
free (events);
close (sfd);
return EXIT_SUCCESS;
}
|
